On-screen displays (OSD) allow television and other display viewers to perform increasingly complex functions such as controlling settings for the television or display and menu selections for digital video recorders (DVRs) attached to the television. OSDs generally result from the video processor that operates the display. These video processors are typically highly integrated systems on a chip (SOC) and process input signals from a variety of sources for display by the television system, such as a flat panel or projector display.
The complexity of the SOCs makes them hard to program and software development times are becoming longer and more expensive. Manufacturers therefore tend to use the same SOC across all of their displays, leading to very little difference in image quality between the displays at the top and bottom of the product line.
The SOCs typically has only one output. This results in any post processing of the image after the SOC being applied to both the image and the OSD. When images are ‘upscaled’ or the frame rate is increased, this post processing actually degrades the appearance of the OSD. The one output also results in no post processing occurring if the OSD is to overlay the image. This may cause problems especially with ‘transparent’ OSDs, where the image can be seen ‘through’ the OSD.